Earth-skimming tau neutrinos: air Cherenkov signals from tau decays

Detection of the flux of very-high energy cosmic neutrinos is a key measurement to understand the highest energy processes in the universe. In particular, neutrinos that originate from ultra-high energy cosmic ray interactions with background photons is crucial to understand the highest energy cosmic rays. Using the Earth as a neutrino converter, satellite-based or balloon-based detectors have the potential to measure the flux of tau neutrinos that yield upward-going extensive air showers (EAS) from tau decays. Using the Probe of Extreme Multi-Messenger Astrophysics (POEMMA) mission’s detector capabilities for EAS Cherenkov signals at an orbital altitude of 525 km as an example, we discuss the simulation process and neutrino sensitivity for neutrino energies above 10 PeV for isotropic fluxes like the cosmogenic neutrino flux and for neutrino point source target-of-opportunities.